For targeted diagnosis, sputum examination is the method of choice (microscopic, cultural and, if possible, molecular biology), additionally X-ray absorption.

If there are further ambiguities, bronchoscopy should also be performed with targeted aspiration.

The Tuberculin Skin Test (Mendel-Mantoux test) is preferred for screening.

In case of a a tuberculosis-infected population, X-ray absorption is preferred.
(Symposium "Current Infectiology", Wiesbaden, 6.-10.4.2002, MMW.Fortschr.Med.No. 40/2002)

The following also applies:

Negative laboratory results do not exclude tuberculosis requiring treatment.
(Prof.Dr.K. Feldmann, Munich-Gauting, DBI Der Bay. Int.21 (2001) Nr4)